Instructions for the installer
46
3.18.3 Gas valve setting
Maximum heating output adjustment
•
Check the flow pressure value (see
Operating data
on page
22
);
•
Remove the plastic cover
A
at the top of the modulator coil, protecting the pressure regulator adjuster screws;
• Connect a pressure gauge to the pressure measurement point
IN
to check the input
OUT
and the output pressure;
•
Press the button “
+ DHW
” until a value of 50°C is shown on the LCD display and open one or two domestic hot water taps to allow
the boiler to operate at full power;
•
Rotate the brass adjustment nut
B
CLOCKWISE as far as it will go to increase pressure to the nozzles, rotate ANTI-CLOCKWISE
to reduce pressure to nozzles;
• For LPG operation, tighten the nut
B
completely in a CLOCKWISE direction.
Minimum heating output adjustment
• Disconnect electrical power from the modulator spindle.
D
;
•
Switch on the burner and check that the "MINIMUM" pressure value matches the value indicated (see
Operating data
on page
22
);
•
To adjust the pressure, hold the brass nut
B
in place using a 10mm spanner (fig. 23, fig. 24 or fig. 25) and turn the plastic screw
C
CLOCKWISE to increase the pressure, or ANTICLOCKWISE to reduce it;
•
Re-connect the electrical wiring to modulation coil.
Final settings
• turn the boiler on and check its correct operation;
• measure the minimum and maximum gas valve pressures again;
•
adjust as necessary.
•
e-fit the plastic cover
A
on to the screws;
• close gas pressure test points;
• check for gas leaks.
A
C
B
D
OUT
IN
Fig. 21 SIEMENS VGU56
OUT
D
IN
A
C
B
Fig. 22 SIT 845
A
C
B
IN
OUT
D
Fig. 23 SIEMENS VGUS56
